TPD1E10B09: What's the recommended schematic for a microphone input with phantom power and ESD protection with TPD1E10B09?

Hi Jay.

When choosing an ESD diode, you must make sure to choose a working voltage (Vrwm) that is at least the max voltage on the line you're protecting. Can you confirm the max voltage on the input line?

Regards,

Sebastian 

That's a good question the device is a tov320adc6140 and it does have some esd protection built in, it appears. Is that true?

It's a 3.3v device, if that answers your question?

That's a good question the device is a tov320adc6140 and it does have some esd protection built in, it appears. Is that true?

Section 7.2  ESD Ratings

It's a 3.3v device, if that answers your question?

For a microphone input with phantom power would your recommend just following the schematic for the TLV320ADC6140EVM module? Is it the case that ESD protection might be overkill for most basic audio applications?

Thank you Sebastian,

Should it be placed before or after the DC coupling cap (to ground). Our product has phantom power on the inputs. 

Jay

Hello Sebastian, 

I know you can't give out specifics for each customer's specs, but I wonder if the following schematic makes sense to you for an input stage including EMI and some RF filtering for the TLV320ADC6140?

The ferrite bead to remove some RF, then a path to ground at R101, then the coupling cap, and finally a TPD1E10B06 for ESD protection directly before the IC input. What do you think?

i'm going to stick with the fact that we don't need an antialiasing filter according to this document (https://www.ti.com/lit/an/sbaa377a/sbaa377a.pdf?ts=1675179442664&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTLV320ADC6140)

Jay

Sebastian Muriel said:

I always recommend adding ESD protection near exposed connectors that are being unplugged, I'd recommend the TPD1E10B06 in this case. 

PS - the device you recommended is a 5.5v device. Does this still make sense being that I'm supplying the TLV320 with 3.3v? 

Hi Jay,

Are you connecting the input of the ADC to a 48 V supply directly? 

If the line is 3.6 V, than a 5.5 V device works fine. You can use the 3.6 V version TPD1E1B04. 

ESD diodes are most effective close to the ESD source, in most cases the connector. The same can be said for ferrite beads if you want to use them for EMI protection. I would recommend placing the ESD diode before the coupling cap as close as possible to the connector. 

Regards,

Sebastian

Thank you Sebastian for your comments, this is very helpful. 

The 48V phantom power is connected to the line through a 6.8k resistor to the input, prior to the connector. So my concern is the ESD device taking the 48V and considering that an ESD event. My assumption therefore, is that I must place the ESD protection after the decoupling capacitor, otherwise the phantom power will eliminate the ESD protection and send the 48v to ground whenever it's turned on.

Does this ring true?

Hi Jay,

Yes in this case you should place the ESD diode after the coupling capacitor. The ESD strikes are AC events so they will pass through the coupling capacitor but the diode won't be affected by the 48V after the coupling capacitor. Make sure to choose an appropriate voltage rating for the capacitor. 

Regards,

Sebastian